On Wed, 27 Aug 1997 16:05:56 MDT, you said:
> Mostly sites seem to be using this to tell where mail comes from
> exclusively.  If it doesn't resolve (as in the case of a blank) then it
> doesn't get there.

Supporting MAIL FROM:<> is *REQUIRED* by RFC1123, section 5.2.9.  This
is a  clarification of RFC821, section  4.1.2.   It's how mail daemons
send  back errors in a way  guaranteed not to loop  (think about if it
came back with a non-null MAIL FROM - you could get two mailer daemons
sending each other error messages).

I've gotten sufficiently fed up with  sites that are that unclued that
I'm in the process of writing auto-flame  scripts for Procmail to deal
with it when Listserv sends me the bounce message.

I would suspect that mail from a  list always has  the MAIL FROM: set,
but mail that has 'From: listserv@hostname' in the RFC822 headers will
go  out with a null MAIL  FROM.   However, Eric or   Nathan is free to
correct me on this ;)

--
                                Valdis Kletnieks
                                Computer Systems Senior Engineer
                                Virginia Tech